This invention provides systems for general mass transfer of solubles and suspended particles from a gas to a liquid. Such systems are applicable to any industrial process which produces gases carrying soluble or partially soluble gases or wettable or soluble solids which must be scrubbed from the gas. For example, vapor deposition and etching processes such as those employed in the semiconductor industry produce gases which are laden with solubles including hydrochloric acid, hydrofluoric acid, nitric acid, ammonia, metal halides and other halogen compounds. These gases must be scrubbed free of such contaminants before venting to the environment or captured for other uses or reuse.
Conventional gas scrubbers generally employ filter media such as packed beds or mixing apparatus such as rotatable cylinders for scrubbing solubles or suspended particles from the gas. U.S. Pat. No. 4,762,539 discloses such a scrubber wherein one or more rotatable cylinders having perforations for passage of smoke are partially immersed in a liquid bath contained in a scrubbing chamber. The cylinders include cups along their axes for spilling liquid over the cylinders during rotation. Smoke laden with particulate impurities is propelled through the perforations as the cylinders rotate. The cups collect and spill liquid from the bath over the cylinders as smoke is forced through the perforations of all of the cylinders to the interior of the innermost cylinder and from there through the perforations to the outermost cylinder, whereby the gas is washed free of particulate impurities.
Another scrubber for removing solubles from gas is disclosed in U.S. Pat. No. 5,011,520 wherein a stream of gas passes from a negative pressure stage (where it is sprayed by a scrubbing liquid) through a constricted region of the scrubber into a main scrubbing chamber. In the main chamber the gas effluent is again sprayed with scrubbing liquid in an upper region of the chamber. The gas and scrubbing liquid move to a central region of the chamber where a media filters and mixes the gas and scrubbing liquid. A lower separation region of the chamber separates and discharges the scrubbed gas. The scrubbing liquid laden with contaminants removed from the gas moves through a diverter plate at the lower boundary of the separation region and into a lowermost region of the chamber.
U.S. Pat. No. 5,185,016 discloses a gas scrubber having a rotatable turbine with blades at its periphery and openings along its axis. The turbine is housed within a chamber containing a body of liquid. A stator partially surrounds the rotatable turbine and forms a channel therebetween. The channel communicates with the body of liquid in which the blades of the turbine dip. Waste gas is fed into the rotating turbine along its axis and passes through its openings to the periphery, whereby the gas and liquid from the liquid body mix in a turbulent fashion within the channel.